Flash Flood Warning 9, NWS Phoenix, AZ

656 
WGUS75 KPSR 220248
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
748 PM MST Sun Jul 21 2019

AZC013-220615-
/O.CON.KPSR.FF.W.0009.000000T0000Z-190722T0615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
748 PM MST Sun Jul 21 2019

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1115 PM MST FOR
MARICOPA COUNTY...

At 747 PM MST, Doppler radar indicated thunderstorms have ended, but 
produced heavy rain across the warned area. Up to two inches of rain 
have already fallen since 630 pm. Flash flooding is expected to 
begin shortly.

Flash flooding will remain over mainly rural areas of Maricopa
County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, country roads, farmland, and other low lying
spots.

&&

LAT...LON 3262 11269 3274 11274 3281 11259 3260 11247
      3251 11249 3251 11269

$$

18

991 
WGUS75 KPSR 220447
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
947 PM MST Sun Jul 21 2019

AZC013-220457-
/O.CAN.KPSR.FF.W.0009.000000T0000Z-190722T0615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
947 PM MST Sun Jul 21 2019

...THE FLASH FLOOD WARNING FOR MARICOPA COUNTY IS CANCELLED...

The heavy rain has ended. Flood waters have receded. Flooding is no
longer expected to pose a threat. Please continue to heed any
remaining road closures.

LAT...LON 3262 11269 3274 11274 3281 11259 3260 11247
      3251 11249 3251 11269

$$

18

Area Forecast Discussion...Updated
National Weather Service Phoenix AZ
520 PM MST Sun Jul 21 2019

.UPDATE...Updated aviation discussion.

&&

.SYNOPSIS...
Dry and seasonably warm conditions will continue today with most
shower and thunderstorm activity remaining well south of Phoenix
this afternoon. Moisture will increase Monday and Tuesday providing
better chances of thunderstorms and strong outflow winds for the
first half of the week across the lower deserts and also including
western areas. Slight chances for thunderstorms will continue for
the remainder of the week, along with a modest warm up.

&&

.DISCUSSION...
Monsoon activity looks to increase across the state, and potentially
the lower desert, over the next few days. Last night, a moisture
surge from the Gulf of California improved the moisture profile for
the lower atmosphere as reflected by widespread surface dew points
in the 60s to 70s range this morning. However, the 21/12Z sounding
in Phoenix revealed significant dry air in the mid and upper levels.
The Tucson sounding did show thick moisture through the midlevels
indicating quality moisture for robust monsoon activity is
established across the southern portion of Arizona.

Current mesoanalysis depicts a tongue of the deeper moisture
protruding into southern Pinal and Maricopa Counties. This area will
see an increase in instability through the early afternoon as clear
skies have allowed for plenty of daytime surface heating. Storms
have already formed west of Tucson and various high resolution
models depict thunderstorm activity increasing along the US/Mexico
border and in western Pima County. Given the lack of moisture
further north, storm activity will struggle to reach our forecast
area but some outflows and isolated thunderstorms may develop in
southern Maricopa and Pinal County at the apex of the aforementioned
moisture protrusion. While convection potential here looks limited,
storms and outflows may create a dust hazard late for the Interstate-
8 corridor.

Sunday's convection will likely enhance the moisture profile for
Phoenix and other areas overnight into Monday. Synoptically, the H5
high will also expand and recenter slightly north of the Four
corners area enhancing the easterly midlevel flow over Arizona while
a cold front extending across the Continental Divide drives
southward. With this setup, the easterly flow should be able to draw
easterly disturbances into the Southwest Monday afternoon. Given the
anticipated enhanced moisture, disturbances and instability, models
indicate thunderstorm activity increasing in the High Country, Rim
and southern Arizona by the early afternoon. The growing concern is
that any outflow(s) will have the potential for creating widespread
blowing dust across the Phoenix area and elsewhere. Western Arizona
and southeast California may also see activity very late Monday into
Tuesday if any of these outflows become long-lived as additional
convection reinforces the boundary. Depending on Monday's
thunderstorm activity, Tuesday also has the makings of another
active monsoon day but with hints of better rainfall potential as
GEFS plumes show better QPF totals. Nevertheless, any storms on
either day will contain the potential for producing strong gusty
winds and localized heavy rainfall.

The outlook for the rest of the week is murky as the forecast can
change drastically depending on convection from the day before. By
midweek, a passing trough across the northern US will dampen the
amplitude of the H5 high and pushing the center closer overhead.
Enough moisture will linger in the area to provide non- zero storm
chances through the week although most monsoon activity will favor
the higher terrain across Arizona.

&&

.AVIATION...Updated at 0020 UTC

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Today to be the last day with no convective threats in the greater
Phoenix area. Minimal CAPE and weak steering flow should keep storms
well out of the area. Expect that to change Monday, but do not
expect any storms or outflows into the terminals until the evening
hours Monday - likely after 02-03z.

Overall, winds tonight into Monday should favor the west most of the
period, especially at KPHX. KPHX may see just a few hours of light
variable or light east after 11z before returning to the west. Look
for a few hours this evening with westerly gusts into the teens
before gusts diminish and sustained west winds return 10k or less.

Look for increasing mid/high clouds overnight tonight and continuing
much of the day Monday. Expect SCT-BKN decks mainly aoa 14kt feet
with FEW high based cu decks during the afternoon on Monday.

Southeast California/Southwest Arizona including KIPL and KBLH:

No significant aviation issues expected over the western deserts.
Expect variable amounts of mainly high clouds with lots of BKN high
level decks aoa 18k feet over the next 24 hours. Winds to favor the
southeast during the TAF period at KIPL with some gusts into the
teens this evening. Winds favor the south at KBLH mainly 15kt or
less with some gusts possible early this evening and again Monday
afternoon.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Wednesday through Sunday:
There are no significant changes to the outlook. Temperatures will
undergo a slight warming trend heading into next weekend but still
typical for this time of year. Lingering moisture will allow for
storm potential in all areas, although favoring the higher
terrain north and east of Phoenix. Thunderstorms will likely
produce gusty outflow winds capable of sudden directional changes.
Otherwise, winds will tend towards typical diurnal
upslope/downslope patterns with afternoon breezes. Min RH values
will drop into the 15-20% range with weak to fair overnight
recoveries of 25-50%.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

DISCUSSION...Deems
AVIATION...CB
FIRE WEATHER...Deems